Preload constant mesh gearbox

Details Preload constant mesh gearbox Preload constant mesh gearbox

1999-09-17

2001-05-01

Estremsky, Sherry (Department: 3681)

Machine element or mechanism

Gearing

Interchangeably locked

C074S361000, C192S084300

Reexamination Certificate

active

06223613

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to improvements in gear systems. More particularly, the improved gear system of the present invention is intended to, inter alia, allow changing of gears under load without the need for a traditional clutch and with the substantial minimisation of any momentary reduction in power input to the gear system.
DISCUSSION OF THE PRIOR ART
Constant mesh gear boxes generally rely on a means to lack and unlock individual gears with respect to a drive shaft. Unlocking a gear disengages that gear ratio and allows it to rotate freely about the shaft.
Locking a gear with respect to the shaft causes that gear ratio to be engaged. This allows transmission of power from the shaft in respect of which that gear has been locked to another shaft about which a complimentary gear is provided in fixed relation, at that sear ratio. Such gear pairs or ratios are generally in constant mesh aligned along the length of two substantially parallel shafts. One gear pair or ratio is engaged at any one time whilst the remaining gear pairs or ratios rotate freely about the shaft.
Attempts appear from the prior art to have been made at synchronising the timing of the unlocking of one gear with the concurrent locking of the next gear. It seems that this arrangement does not provide a viable solution as existing methods are slow and dependent on cumbersome and expensive means.
The invention disclosed in International Patent Application POT/AU97/00024 (WO 97/26468) discloses a gear system utilising magnetically driven locking and unlocking of gears with respect to parallel shafts but does not disclose the ability to change gears under load.
Changing of gears in prior art manual and sequential gear boxes results in a break in power transmission and lost acceleration time, as it requires disengaging one gear-wheel pair or ratio prior to engaging the next gear-wheeled pair. Prior art automatic transmissions are typically inefficient whilst manual gear-boxes are slow to change between gears.
The improvement to gear systems of the present invention has as one object thereof to substantially overcome the above-mentioned problems associated with the prior art. For example, to change gears successfully under load requires an engagement of the next gear whilst the presently engaged gear remains engaged also. The locking of the newly engaged gear is not then exposed to such an impact as the previous gear is already bearing the load. The newly engaged gear then assumes the load from the previous gear allowing that previous gear to unlock freely from its shaft.
Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
BRIEF DESCRIPTION OF THE INVENTION
In accordance with the present invention, there is provided an improved gear system characterized by at least one gear-wheel provided about a shaft, the shaft and the or each gear-wheel being provided with means for actuable engagement therebetween in both rotational and counter-rotational directions, such that engagement of the means for actuable engagement of the or each gear wheel in both the rotational and counter-rotational directions causes the or each gear-wheel to rotate in conjunction with the shaft and prevents such from counter-rotating relative to the shaft disengagement of the means for actuable engagement of the or each gear-wheel in both the rotational and counter-rotational directions allows the or each gear-wheel to rotate independently of the shaft and counter-rotate relative to the shaft, engagement of the means for actual engagement in the rotational direction and disengagement of the means for actual engagement in the counter-rotational direction of the or each gear wheel causes such to rotate in conjunction with the shaft and allows such to counter rotate relative to the shaft, and engagement of the means for actual engagement in the counter-rotational direction and disengagement of the means for actual engagement in the rotational direction of the or each gear wheel allows such to rotate relative to the shaft, but prevents such from counter rotating relative to the shaft.
In one form of the invention, the means for actuable engagement is provided in the form of at least one pair of pawl members comprising forward and reverse pawl members provided in the shaft or in the or each gear-wheel, wherein the forward pawl member is adapted to engage a leading surface of a substantially complimentary recess in an opposed surface positively during rotation of that opposed surface with respect to the pawl member, and the reverse pawl member is adapted to engage a trailing surface of a substantially complimentary recess in an opposed surface positively during rotation of that opposed surface with respect to the pawl member.
Preferably, the forward and reverse pawl members are caused to engage the complimentary recesses at least in part by magnetic means.
The magnetic means may include a roving magnet provided within the shaft such that the or each pawl member is magnetised in a manner whereby positioning of the roving magnet directly alongside the pawl members causes those pawls to be repulsed or attracted by the roving magnet and to project into the substantially complimentary recess in the opposed surface.
Preferably, the magnetic means includes a roving electromagnet provided within the shaft, whereby positioning of the roving electromagnet directly alongside the pawl members causes those pawls to be repulsed or attracted by the roving electromagnet (when actuated) and to project into the substantially complimentary recess in the opposed surface.
Preferably still, the roving electromagnet comprises a solenoid.
In a highly preferred form of the present invention, the improved gear system is further characterized by a pair of substantially parallel shafts, each shaft having provided thereabout at least two gear-wheels forming gear-wheel pairs or ratios between the parallel shafts.
In one form of the invention neither of the gear-wheels of a gear-wheel pair or ratio are permanently fixed with respect to its shaft in order to minimise friction losses caused by rotation of all gear-wheel pairs.
In an alternate form of the invention the gear-wheels of a gear-wheel pair or ratio are permanently fixed with respect to one said shaft.
Preferably, each shaft and/or a casing or housing provided about each shaft and the gear wheels located thereabout has provided therein an arrangement or array of electromagnets, the array of electromagnets being positioned so as to allow selective actuation of one or more of the electromagnets to result in selective engagement of chosen gear-wheels with their respective shafts passing therethrough. Preferably still, the array of electromagnets is provided within each shaft.
In a highly preferred form of the invention a programmable logic controller (PLC), microprocessor, computer or engine management system is provided to govern actuation of the array of electromagnets.
In one form of the invention, each shaft may further comprise a plurality of rotating lock rings interposed between a hollow central static shaft through which a roving solenoid assembly may traverse, and a driving/driven rotating shaft having pawl members pivotally mounted thereon, capable of selectively engaging the gear wheels the roving solenoid assembly being adapted to momentarily cease the rotation of one of the plurality of lock rings, which in turn acts on a pawl member and engages or disengages a selected gear wheel. Preferably, each gear wheel has associated therewith four of said rotating lock rings.
Preferably still, pairs of said rotating lock rings comprising said four have associated therewith at least one of said pawl members. Further and still preferably, adjacent pairs of said rotating lock rings have three of said pawl members associated therewith, and arranged circumferentiall

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